Long period pendulum



Sept. 10, 1946. Y G, Q SCOTT v 2,407,580y

' LONG PERIOD PENDULUM Filed Feb. l5, 1945 Patented Sept. 10, 1946 LONG PERIOD PENDULUM Gifford G. Scott, Detroit, Mich., assignor to Gen-` eral Motors Corporation poration of Delaware Detroit, Mich., a cor- Application lFebruary/.15, 1945, Serial No. 578,025

3 Claims. l

This invention relates to stabilizing means and more particularly to control means for maintaining supports for certain apparatus in a level position. It is often desirable when using certain measuring or testing or control equipment which is in turn mounted upon mobile vehicles to maintain the equipment in as level as a position as possible to avoid errors which may be introduced into the operation of the system due to tipping, tilting, etc. In order to provide such a stabilization or level maintenance it is, of course, necessary to have some means actuated by rolling or pitching to control leveling means and which in turn will have a long period and not be subject to short rapid fluctuations which would tend to too readily actuate corrective measures.

It is therefore an object of my invention to provide a long period gravity actuated control.

It is a further object of my invention to provide stabilizing or leveling means for maintaining equipment in a predetermined position in which the restoring force of the suspension is small compared to the gravitational force due to unbalance.

It is a still further object of my invention to provide an immersed ily wheel acting as a long period pendulum to control stabilizing or leveling means.

With these and other objects in view which will become apparent as the specification proceeds, my invention will be best understood by reference to the following specification and claims and the illustrations in the accompanying drawing, in which:

Figure 1 is a vertical section taken through the control means of my invention.

Figure 2 is a side elevation of my control pendulum, parts being broken away and shown in section.

Referring now more speciilcally to the drawing, there is shown therein a housing 2 having a cylindrical portion and transparent side panels within which there is pivotally mounted on a ribbon 4 a transparent or Lucite ily wheel 6, one portion of the fly wheel being slightly weighted so that it tends to remain in a given rotative position upon its axis. The ends of the ribbon are clamped in the sides of the housing by suitable retaining set screws 8 and I0. A yoke Il has formed on one end bushing I2 which supports an arm I4 carrying a housing I6 in which a source of light I8 is mounted. One side of the housing and that portion actually supported by the bracket lil is a small cylindrical tube carrying a concentrating lens at its outer extremity directing light through the transparent sides 22 and 2li of the housing 2 and through a portion cf the Lucite ily wheel E.

On the opposite end of yoke l I and on the opposite side of the housing 2 is a second bushing I3 carrying arm I5 upon which a photo-electric or sensitized cell 2t is mounted to be affected by light shining from the source through thely wheel. The housing is likewise filled with a liquid 28 having about the same specific gravity as the material of the ily wheel, Vfor example, Lucite to assist in supporting the same. The wheel itself is painted with an opaque paint over one half of its area as shown at 30 in Figure 2 so that light can freely pass through half of the ily wheel but not the other half. Thus, as the fly wheel rotates about its axis, if the dividing line 32 is so positioned as to intercept the beam ozf light thrown from the source of light i8 to the photo cell 2t, any rotation would either cut oil` the ilow of light or in the inverse direction permit ilow 0i :the same, thus applying a series of pulses or energized periods to the photo cell.

It is intended that the mechanism be mounted upon the part to be leveled and should control, through the photo cell, the driving means for moving the platform or support to its new position, the actual movement of the same therefore acting as a follow-up means to return the fly wheel to its original or neutral position. The use of the ribbon support for the ily wheel is to provide a support giving practically no static friction and very small restoring forces as compared to the gravitational force on the unbalance of the ily wheel, and by using liquid of approximately the same specific gravity as the ily wheel most of the force tending to sag the suspension will be removed and there will be obtained a proper amount of friction to obtain critical damping. The actual gravitational force is relatively small and since the fly wheel is damped the period of the same is long and I obtain in effect a long period pendulum action.

It will thus be obvious that by mounting the construction as shown upon a platform to be maintained in a substantially level position that any tendency of the same to move to a new position will cause the fly wheel to tend to rotate either cutting oil or permitting the flow of light to the photo cell which in turn would control a driving motor (not shown) to return the platform to its original level position. It will, of course, be also obvious that the mechanism must be adjusted initially so that the beam of light aioms falls upon the intersecting line 32 before the apparatus is put in operation, and for this purpose the yoke supporting the housing of the source of light I8 and the cell is adjustable around the axis or ribbon 4 to provide the correct initial index.

I claim:

1. In stabilizing means, a source of light, a light sensitive cell, a light intercepting pendulum pivotally mounted between the source and cell` and transparent damping means in which the intercepting pendulum is immersed having approximately the same specific gravity as the material of Athe light intercepting pendulum.

2. In stabilizing means, a casing having tranc- S parent Walls, an unbalanced Wheel formed of transparent material, an opaque coating onv a portion of said whee1, a thin ribbon suspension for said Wheel in said casing, damping means in ing means in said casing immersing said wheel,

a source of light and a photo sensitive cell mounted on opposite sides of said casing so that the light from the source tothe cell passes through the casing and a section of the wheel and the wheel area controls the flow.

GIFFORD G. SCOTT. 

